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GPR testing on an above grade slab
(lemmy.ca)
Anyone care to offer their interpretation on the data displayed? ;)
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this post was submitted on 26 Sep 2024
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Not a geologist. Clearly the best best lasagna can be found at depths below 2m.
But seriously, what are we looking at? I assume the solid white line at 0m is the slab itself. What's the wavy white line just below 0m?
Wavey line is rebar -- the radar reflections take the shape of hyperbola as you pass over them. Bottom of the concrete is just below the rebar (those hyperbola overprint it a bit, so it's harder to see). Then it's crushed rock fill (probably limestone) until the two metre mark.
Very cool, thanks for the explanation. What's the purpose of the inspection? Is it to verify the correct slab and/or subgrade thickness? Or the presence of rebar?
In my particular case, the purpose was testing the equipment over a target that I can use to confirm it is working as expected.
But GPR in concrete can be used for all the purposes you mention. It can also be used to find voids, verify "as-built" drawings, etc. Some of our clients use it simply to avoid drilling into rebar when installing anchor bolts for shelving or whatever.
My background isn't concrete, so I don't do the more advanced things with it :)